Polylines with real arcs for CNC Router?

If the user closes the Save Dialog when saving a DXF instead of providing a file name there is a save error. You only see the error if you have the Ruby Console opened prior to Clicking the Export button.

Garry,
I think this is true, up and until one explodes Component#2 which is fine for me. I can one step undo this to preserve editing of nested components, as long as I perform the explode to all in one go…export…undo.

One more problem I ran into is some of my parts & holes move once exported.
I am sure this has to do with the fact they are “flipped” to nest on the 4x8 sheet.
If there is anything I can do to make them stay put…I’m all ears. (understanding the simple part of the extension)

please see .skp
GkWare_Expt_NestTest_07_23_2018.skp (270.4 KB)

Best regards,
Charlie

I can duplicate the issue if the holes and plates are components. Turns out the T can be rotated 180 degrees and that does work fine.

image

Also - if the holes and plates are groups then you can flip the parts.

I will look into this some more. I’m thinking that the transformation (during the flip) is getting missed.

Garry,
Thanks again…don’t go to a lot of trouble.
I may just go with my original thought of basically exploding all and grouping by layer after all…four step undo…instead of one…but all good…you have the arcs behaving nicely and that is the main thing.

Charlie

I spent just a bit of time with this. Essentially the part is getting rotated around the axis by 180 degrees instead of mirrored on the X axis. I modified 2 lines for each insert and got predictable results when importing into CAD.

I believe that all I will need to do is modify the DXF write and the DXF read to support flipping (or scaling -1)

This plugin should solve the problem:

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Simple DXF is now at version 1.0.5
It has a flattening button that handles angled parts

image

And it handles entry point for CNC
Faces handle CW or CCW direction and the start pin controls creation order of the polyline.

image

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I am having no luck getting true arcs out of Simple DXF. All fo my exported files so far using the extension are faceted in the .dxf Is there a way to specify 2d or 3d output in the extension so that Circle and Arc info is retained in the output dxf?

I wonder if Simple DXF has the same step you need to do with the built in exporter? With the built in exporter you get real arcs by exporting as DXF as a 3D model, not 2D model. But, you also need to deselect Faces in the export options, otherwise you get the true arcs from the edges, but that is overlaid with line segments from exporting the faces as well.

If possible, share the SU file you are working with. What version of SU are you running?

He’s running SketchUp 2022 as indicated in his profile.

What version are YOU running? Please complete your forum profile.

My version is SU 2020

Sure, here is a file that fails in .dxf. Same file in SU22 and SU 20. This failure does not manifest when sharing in .dxf format between CAD programs, if you open an export in a CAD viewer is will appear correct, but flips arcs when opened by CAM software. @mpoole32 I have seen you are a Simple DXF user in previous post in '19, are you still using it successfully? I can process this export through SimpleDXF and the arc flipping problem is indeed cured but the arcs are all faceted, I must be missing something. Making the “group within a group” is a bit tedious to make the extension function but I would use it if it worked. I saw @ChrisDizon was working on a ruby script that might solve the arc flips a few years ago, but I don’t know where that project ended up.

There does not appear to be any options for export when using SimpleDXF as with the native exporter. @IanT appears to have had some success using SimpleDXF to prevent arc flipping when creating tollbooths in previous posts, but I haven’t seen them around for awhile.

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@endlessfix I’m not sure what type entity a “curve” is in SU but that’s what your original shows up as.

When exploded you get line segments. I simply recreated it using arcs and straight lines and did the SimpleDXF export and then reimported it. Seemed to work as expected.
Slewing Track MP32.skp (214.7 KB)
SlewingTest.dxf (1.5 KB)

Thats my fault, wrong file, they should not have been curves, the file I sent was a copy that I had experimented on by welding the perimeter which converts arcs to curves to see if SimpleDXF would behave differently. Here is the true arc file I should have shared.

Slewing Track Steel v20 copy (1).skp (132.0 KB)

Summary

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Could not open that version because it is still 2022 version

Ugh, I’m batting a Zero this morning. Try again, I’ve modified the post. Thanks!

the dxf you send looks good in CAD viewer but when I put into the best CAM emulator I have found it looks faceted. Maybe it’s a problem with my viewer. Are you choosing 3D in any way on Simple DXF or is that automatic?

That revised 2nd upload worked fine as 2020 version and for simple dxf.
Slewing Track Steel v20 copy Hopeful.skp (200.4 KB)
SlewingTestwArcs.dxf (1.6 KB)

You may have missed a step when it came to processing your original geometry with Simple.
From the instructions.

Your original shape needs to be in a group and each additional hole needs to be in a group by itself. Then all of those groups should be included in a group.

Take a look at the the DXF I’ve included and see if that is what you were after.

I open dxfs in Turbocad to check for accuracy need by g-code generations software. When I open that test dxf of you item in Turbocad I see that it is a polyline. When exploded once I see arcs and lines which is what I need dxfs to consist of. This works with both 2-D and 3-D coming from SU.